Metrohm 756 KF Coulometer - Manual (Page 108)

4.3 Properties of the RS 232 Interface
756/831 KF Coulometer, Instructions of Use 100
4.3.2 Pin Assignment
RS232C Interface
Transmitted Data (TxD).
If no data are transmitted, the line is held in the “ON” condition. Data
will only be sent when CTS is in the ”ON” condition.
Received Data (RxD)
Request to Send (RTS)
ON condition: Coulometer is ready to send data.
Clear to Send (CTS)
ON condition: Remote station is ready to receive data.
Signal ground (GND)
Data Terminal Ready (DTR)
ON condition: Instrument is ready to receive data.
Protective earthing
Direct connection from cable plug to the protective ground of the instrument.
Polarity allocation of the signals
- Data lines (TxD, RxD)
voltage negative (<-3 V): signal state ”ON”
voltage positive (>+3 V): signal state ”ZERO”
- control or message lines (CTS, RTS, DTR)
voltage negative (<-3 V): OFF state
voltage positive (>+3 V): ON state
In the transitional range from +3 V to -3 V the signal state is undefined.
Driver 14C88 according to EIA RS 232C specification
Receiver 14C89 " "
Pin 4
Data Terminal Ready
Pin 5
Signal Ground
Pin 8
Clear To Send
Pin 7
Request To Send
Pin 2
Received Data
Pin 3
Transmitted Data